Building an acoustic guitar

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For a few years now I’ve wanted to build my own acoustic guitar. Partly because I love building things, and partly because I wanted something really unusual – but more on that later. This project seems to really intrigue people. I’m often being asked how it’s going so I thought I’d start to keep a proper record of the build.

First let me declare that I am not a luthier or a carpenter and I’ve never done this before. So don’t take my words as gospel. I’m going to be relying on books, YouTube videos and years of experience as a player.

Choosing wood to build an acoustic guitar

This being my first build, I’ve elected to go for cheap woods. The top or soundboard will be Red Cedar; known for being a little warmer and less controlled than Sitka Spruce – this will lend itself well to a finger-style guitar and potentially less of a strumming-machine.

The Back and sides will be Sapele. With similar characteristics to Mahogany; There should be a nice balance here of bottom end and clarity. I’m hoping this will help keep the Cedar in check!

Finally the internal bracing, kerfling and end blocks will be made from Mahogany and Spruce.

Tools

This is where the cost can really start to rack up. Not only are there dozens of tools needed, but they’re all bespoke luthier tools. To keep the cost down I’m following a book that uses traditional methods and therefore barely any power tools.

That being said, I did buy a cheap jigsaw to help make the MDF mould for the body. I feel it’ll be useful further down the line too.

Beyond that I’ve also bought:

  • A set of chisels
  • A smoothing plane
  • A block plane (which I’m going to modify into a toothing plane)
  • 4 ‘F’ clamps (although I suspect I’ll need more)
  • A hacksaw
  • 2 pairs of callipers
  • 2 Cabinet scrapers (the most underrated but brilliant tool!)
  • A bending iron

I also already have a tool kit with the old faithfuls in it!

I’ve also managed to adapt some more basic tools to fulfil more niche purposes. For example, using a set of files and the hacksaw I’ve managed to turn one of the planes into a toothing plane.

But we’ll cover that later on.

Creating an acoustic template

The first step was decide the shape of the guitar. Ambitiously I aiming for a dreadnought with a cutaway. I’m basing the body on my Martin DCX1RE; the classic Martin Dreadnought.

So the first thing to make is an MDF template in the shape of the Martin. This is simply 3 layers of MDF; each roughly cut out screwed together and then sanded down to make them flush to each other and symmetrical.

It took me days to get this just right. If there’s one comments I have about the videos and books I’m using it’s that they don’t give you any idea of just how long some of these processes take.

That being said, Im pretty happy with the result and ready to move on to the actual build!

Joining the soundboard

Build your own acoustic guitarOne of the key elements of the acoustic guitar is its soundboard or top. This quite literally acts like the skin on a drum; vibrating and wobbling to amplify and enhance the vibrations of the strings.

To achieve this you first need to ‘shoot the board’ or plane down the edges of the book-matched pair until they fit seamlessly together. It’s easy enough to do, but it does take time and a good understanding of how to work with your tools. The tiniest adjustments are needed to shave of smaller and smaller bits of wood.

Once this is done you clamp them together with a thin bead of wood glue. I was amazed that the two bits genuinely are attached now. Even after the top has been worked and thinned, the join is good and strong.

Thinning the wood

This was the first part of the build I had been dreading. When you order the wood it’s around 4 – 5mm thick. The soundboard in particular needs to be around 2.2mm thick. I don’t have any special gear. Just two pairs of callipers, two planes and a couple of cabinet scrapers.

You start by creating diagonal furrows in the wood (this is where the homemade toothing plane came in handy).

Then you alternate between this and the smoothing plane which you run up and down the board with the grain. This removes the furrows from the previous run.

Now you measure to see how thin the wood is and repeat. All in all this process took me around 2 days.

This was the most satisfying step by far. In between each Runyon can pick the wood up and tap it to hear how it’s resonating. The idea here is to try and remove the wood’s natural resonating pitch and replace it with an atonal thud which is less ‘boomy’. Otherwise you’ll end up with a guitar that resonates naturally with certain frequencies and not others. Hopefully this approach will make the sound balanced.

Bending the sides

The same process of thinning applies to the back and sides, but getting the sides right is fundamental to the next step. Bending.

This is without a doubt the scariest part of the build. It’s also the first time I’ve had to buy a specialist piece of gear – and not a cheap one at that. Thankfully it’s mum to the rescue – this year my birthday presents consisted of a bending iron, a wooden mallet and a tool belt!

To begin with I didn’t have a clue how hard to push the wood, or how long it I would take. But slowly you begin to feel when the wood is starting to become malleable.

The wood starts to fizz and pop and slowly it gives up some of the resistance and elasticity. That being said, I have been working on the first side on and off for a number of weeks (the project has slowed down a little at this point).

It really is a case of going slowly and taking your time with it. I have had one accident. The fibres on the outside of one of the bends have torn. It doesn’t seem to be causing any great problems structurally. But it has caused some aesthetic damage. I’ve thought about scrapping the wood and buying more. But I think I need to carry on and see how the whole build goes before I invest in more wood.

Fitting the side into the mould

For the first time now I feel like I have achieved something. The first side is in the mould and I’ve built my own clamps to keep the wood in place as I work.┬áThese are simply some threaded rods and turnbuckles with rough cut MDF at each end.

To see this clamped into the workbench, and finally starting to take shape is what has triggered me to start this blog. I can start to see the next steps falling into place.

Now I need to get the second, much harder, side bent into the mould and I can start to look at getting the top braced and glued to the sides.

I began this project on February 6th 2018. It’s now April 22nd. Although it’s worth bearing in mind that I’m only really doing this at the weekends, and even then only when I get the chance. I’ll continue to update this blog as I go, but for now. It’s back to the workshop!

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